init: make initrd/initramfs decompression failure a KERN_EMERG event

Impact: More consistent behaviour, avoid policy in the kernel

Upgrade/downgrade initrd/initramfs decompression failure from
inconsistently a panic or a KERN_ALERT message to a KERN_EMERG event.
It is, however, possible do design a system which can recover from
this (using the kernel builtin code and/or the internal initramfs),
which means this is policy, not a technical necessity.

A good way to handle this would be to have a panic-level=X option, to
force a panic on a printk above a certain level.  That is a separate
patch, however.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

init/do_mounts_rd.c

@@ -83,7 +83,8 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
 		printk(KERN_NOTICE "RAMDISK: %s image found at block %d\n",
 		       compress_name, start_block);
 		if (!*decompressor)
-			printk(KERN_CRIT "RAMDISK: %s decompressor not configured!\n",
+			printk(KERN_EMERG
+			       "RAMDISK: %s decompressor not configured!\n",
 			       compress_name);
 		nblocks = 0;
 		goto done;

init/initramfs.c

@@ -528,7 +528,7 @@ static int __init populate_rootfs(void)
 	char *err = unpack_to_rootfs(__initramfs_start,
 			 __initramfs_end - __initramfs_start, 0);
 	if (err)
-		panic(err);
+		panic(err);	/* Failed to decompress INTERNAL initramfs */
 	if (initrd_start) {
 #ifdef CONFIG_BLK_DEV_RAM
 		int fd;
@@ -554,9 +554,12 @@ static int __init populate_rootfs(void)
 		printk(KERN_INFO "Unpacking initramfs...");
 		err = unpack_to_rootfs((char *)initrd_start,
 			initrd_end - initrd_start, 0);
-		if (err)
-			panic(err);
-		printk(" done\n");
+		if (err) {
+			printk(" failed!\n");
+			printk(KERN_EMERG "%s\n", err);
+		} else {
+			printk(" done\n");
+		}
 		free_initrd();
 #endif
 	}